The inhibitory effect of PN2KPI in human and murine plasma. (A) The clotting time of mouse plasma is prolonged with externally added PN2KPI. (B) FXI activity in human plasma is inhibited by externally added PN2KPI and inhibitory activity is saturated at PN2KPI concentrations > 10μM. (C) Mouse FXI activity is ∼ 75% inhibited by human KPI and inhibitory activity is saturated at PN2KPI concentrations > 10μM.